Add debug counter for ext_dce

Like r15-1610-gb6215065a5b143 (which adds one for late_combine),
adding one for ext_dce is useful to debug some issues with this pass.

Bootstrapped and tested on x86_64-linux-gnu with no regressions.

gcc/ChangeLog:

	* dbgcnt.def (ext_dce): New debug counter.
	* ext-dce.cc (ext_dce_try_optimize_insn): Reject the insn
	if the debug counter says so.
	(ext_dce): Rename to ...
	(ext_dce_execute): This.
	(pass_ext_dce::execute): Update for the name of ext_dce.

Signed-off-by: Andrew Pinski <quic_apinski@quicinc.com>

diff --git a/gcc/dbgcnt.def b/gcc/dbgcnt.def
index e0b9b1b2a76229157dcd8a12444b977ca030b802..ac1f87098493396ffeda42c9e8b49ebf400b81ca 100644 (file)
--- a/gcc/dbgcnt.def
+++ b/gcc/dbgcnt.def
@@ -162,6 +162,7 @@ DEBUG_COUNTER (dom_unreachable_edges)
 DEBUG_COUNTER (dse)
 DEBUG_COUNTER (dse1)
 DEBUG_COUNTER (dse2)
+DEBUG_COUNTER (ext_dce)
 DEBUG_COUNTER (form_fma)
 DEBUG_COUNTER (gcse2_delete)
 DEBUG_COUNTER (gimple_unroll)

diff --git a/gcc/ext-dce.cc b/gcc/ext-dce.cc
index 6c961feee635c38a08ddfdff0b56be422ecfe60f..6d4b8858ec63c794ef1708be13e33dad7cd2e50a 100644 (file)
--- a/gcc/ext-dce.cc
+++ b/gcc/ext-dce.cc
@@ -33,6 +33,7 @@ along with GCC; see the file COPYING3.  If not see
 #include "rtl-iter.h"
 #include "df.h"
 #include "print-rtl.h"
+#include "dbgcnt.h"
 
 /* These should probably move into a C++ class.  */
 static vec<bitmap_head> livein;
@@ -312,6 +313,15 @@ ext_dce_try_optimize_insn (rtx_insn *insn, rtx set)
       print_rtl_single (dump_file, SET_SRC (set));
     }
 
+  /* We decided to turn do the optimization but allow it to be rejected for
+     bisection purposes.  */
+  if (!dbg_cnt (::ext_dce))
+    {
+      if (dump_file)
+       fprintf (dump_file, "Rejected due to debug counter.\n");
+      return;
+    }
+
   new_pattern = simplify_gen_subreg (GET_MODE (src), inner,
                                     GET_MODE (inner), 0);
   /* simplify_gen_subreg may fail in which case NEW_PATTERN will be NULL.
@@ -881,8 +891,8 @@ static bool ext_dce_rd_confluence_n (edge) { return true; }
    are never read.  Turn such extensions into SUBREGs instead which
    can often be propagated away.  */
 
-static void
-ext_dce (void)
+void
+ext_dce_execute (void)
 {
   df_analyze ();
   ext_dce_init ();
@@ -929,7 +939,7 @@ public:
   virtual bool gate (function *) { return flag_ext_dce && optimize > 0; }
   virtual unsigned int execute (function *)
     {
-      ext_dce ();
+      ext_dce_execute ();
       return 0;
     }